Power supply circuits for various loads typically include a converter for supplying a.c. or d.c. current to a load. Such circuits typically include a pair of non-complementary switches in the converter. For example, it is common to use a pair of identical, n-channel enhancement mode MOSFETs as the switches. However, the use of such non-complementary MOSFETs has various drawbacks.
For instance, each of the non-complementary MOSFETs must be controlled by a separate gate-to-source (or control) voltage. This requires level shifting of voltage to couple a single control signal to each of the gate-to-source voltages of the pair of MOSFETs. Such level shifting can be accomplished by a transformer or by conventional bootstrapping means. The transformer method works well at high speeds, e.g., over 20 kilohertz, but is costly and hard to control. The bootstrapping method, usually implemented by an Integrated Circuit (IC), has good control capability, but is unable to work at high speeds, beyond 100 kilohertz..